Sorry and don't mean to be contentious here but I saw the helmet, was at the scene and rode with Dennis all day. It was never stated that his helmet was not fitted properly and it was never stated that he did not have it firmly attached. You made that assumption through other peoples mere random speculation. He had facial, ear and bridge of the nose cuts most likely from the chin bar popping open and the helmet being forced over his head from back to front. This
probably would not have happened with a full face but that too is speculation. Yesterday I stopped in at a shop, with owners permission I tried 5 different HJC flip fronts. I hit the chinbar at the latch release as hard as I dared with the palm of my hand and three popped open (but not every time). Impailing your chin on the front of bike (going over bars) or landing on your chin on impact with ground or into a tree or another vehicle
can force these things to pop open. It is safe to assume that this has happened in
unique cases and will happen in
unique cases. And please note I did say "assume" and "probably" , not "I know" or "absolutely"
Not meant to be an argument, just a clarification

(and yes, I'm most likely a bit too touchy still)
Roamer